This core facility provides analytical chemistry and histopathology support for Projects 1,2, and 3. The neurochemical analysis provided include vasoactive compounds and metabolites measured in serum, cerebrospinal fluid, and microdialysate samples. Amino acids including the nitric oxide related amino acids arginine and citrulline, the excitatory amino acids glutamate and aspartate, the volume regulatory amino acid taurine and the inhibitory amino acid glycine are measured by high performance liquid chromatography. The vasoactive purine adenosine which is elevated during bioenergetic distress is also measured by HPLC. Potassium in microdialysate is elevated with loss of membrane potential maintenance is measured by ion chromatography. The major breakdown products of nitric oxide, nitrate and nitrite, are measured using chemiluminescence. Vasoactive peptides such as endothelin are measured using enzyme- linked immunoassay. Histology support consists of photographic and digital documentation, gross examination, tissue processing, tissue sectioning, and staining. Contusion volume and neuronal cell counting is performed using image analysis software. Using intralumenal markers of capillary perfusion and immunohistochemical markers of capillary endothelial cells, the fraction of perfused capillaries will be measured morphologenically Immunohistochemical staining an also be performed as need; the current repertoire of immunohistochemical staining includes beta-amyloid, glucose and monocarboxylate transporters, endothelin, nitric oxide synthetase (NOS), coagulation factor 8, and 3-nitrotyrosine.